BEIJING, China (CNN) -- A dish of stir-fried pig's liver served at a dinner party in Guangzhou, China, poisoned 14 people with what authorities think was an animal feed additive, a Chinese state-run news agency reported.

The incident comes about a week after 70 people suffered food poisoning after eating pig organs from markets elsewhere in southeast China tainted with the banned food additive clenbuterol.

The victims complained of stomachaches, diarrhea, vomiting and headache, and were taken to a hospital after the Wednesday night party in Guangdong province's capital, Xinhua news agency reported.

Officials were trying to determine whether the diners were suffering from clenbuterol poisoning.

Clenbuterol can prevent pigs from accumulating fat but can be fatal to humans and is banned in China.

One of the largest food poisoning cases involving clenbuterol happened in Shanghai in September 2006, when 336 people were hospitalized after eating pig meat or organs contaminated with the additive, the China Daily newspaper said.